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Effect of Seed Treatments on Sudden Death Syndrome and Yield of Soybean

Yuba Kandel: Iowa State University

<div>Seed treatments have recently been registered for management of sudden death syndrome (SDS) caused by <em>Fusarium virguliforme</em>, one of the most devastating diseases of soybean (<em>Glycine max</em>). We evaluated seed treatment fungicides fluopyram (ILeVO®), thiabendazole (Mertect 340-F®), and a biochemical pesticide, saponins of <em>Chenopodium quinoa</em> (Heads Up®) against their standard base seed treatment in a total of 14 field experiments in Illinois, Indiana, Iowa, Michigan, South Dakota, Wisconsin, and Ontario, Canada during 2015 and 2016. Each of these treatments were evaluated on SDS-resistant and -susceptible cultivars. In 2015, the fluopyram treatment had the least amount of SDS among all fungicides, with nearly 35% less root rot (RR) and 54% lower foliar disease index (FDX), while achieving 6.2% greater yield than the base seed treatment. Resistant cultivars had 30% less RR and 75% lower FDX, with 11% greater yield than susceptible cultivars. In 2016, no seed treatments were significantly different from their base seed treatment, except fluopyram, which had 45% less RR and 44% lower FDX. Seed treatment had no effect on yield in 2016. Resistant cultivars resulted in 23% lower RR and 81% lower FDX, with 10% greater yield, compared to susceptible cultivars. Fluopyram resulted in the greatest reduction in disease compared to the other seed treatment products and can be used as a complement to resistant cultivars for managing SDS.</div>